StarDate Podcast

If you don’t like winter but you live in the northern hemisphere, then give a little thanks to the laws of orbital mechanics. Because of Earth’s lopsided path around the Sun, winter is the shortest season north of the equator. Earth’s orbit around the Sun isn’t a perfect circle. Instead, it’s an ellipse. It looks like a flattened circle, with the Sun slightly away from the center. Because of that shape, our distance to the Sun changes. And that’s where the laws of orbital motion come into play. Johannes Kepler devised those laws more than four centuries ago. One of them says that if you draw a line from the center of the Sun to the center of a planet, as the planet orbits the Sun that line will sweep out equal areas over equal periods of time. To do that, a planet must move fastest when it’s closest to the Sun, and slowest when it’s farthest from the Sun. Earth is closest to the Sun in early January – the start of winter – and farthest at the start of summer, in July. So Earth moves around the Sun in a hurry during northern winter, making the season shorter. This winter, for example, starts at 9:03 a.m. Central Time tomorrow. That’s the moment of the December solstice, when the Sun stands farthest south for the year. The season ends 89 days later. By comparison, this past summer lasted almost 93 days – a longer season thanks to the science of orbits. More about the solstice tomorrow. Script by Damond Benningfield

The “she-goat” is a lot more than it seems. What looks like a single brilliant star is actually two sparklers. Both of them are much bigger, heavier, and brighter than the Sun. Capella is the brightest star of Auriga, the charioteer. Its name comes from a Latin phrase that means the she-goat. It’s 43 light-years away – just down the block by astronomical standards. Both stars of Capella are about two and a half times as massive as the Sun. And both are more than 70 times brighter than the Sun. But the stars are quite close together – less than the distance from Earth to the Sun. So we can’t see them as individual points of light, even with the biggest telescopes. Astronomers discovered Capella’s dual nature with a technique called spectroscopy. It breaks a star’s light into its individual wavelengths. The spectrum of Capella shows two patterns of light. The patterns move back and forth as the stars orbit each other. The patterns reveal details about both stars – their surface temperature, composition, and more. From that and other details, we know that both stars have moved beyond the prime phase of life. Now, they’re in the giant phase. Both stars have puffed up to about 10 times the diameter of the Sun – two big, brilliant stars for the she-goat. Capella is a third of the way up the northeastern sky at nightfall. It’s one of the brightest stars in the entire night sky, so you can’t miss it. Script by Damond Benningfield

The tales that describe many of the ancient constellations can be romantic, tragic, heroic, or majestic. Some, on the other hand, are just weird. An example is Auriga. The constellation is low in the eastern sky at nightfall, and climbs high across the sky later on. It’s marked by a pentagon of stars. It’s easy to pick out thanks to the brightest member of that figure, Capella – one of the brighter stars in the entire night sky. Although Auriga is described as a charioteer, the character usually isn’t depicted with a chariot. But he is shown with a goat and her two kids on his shoulder. There are several versions of his story. In one, he was an early king of Athens. He was raised by the goddess Athena. Among other things, she taught him how to tame horses. He was so good at it that he became the first person to harness four horses to a chariot, like the chariot that carried the Sun across the sky. Zeus, the king of the gods, was so impressed that he placed the charioteer in the stars. The goat is represented by Capella. It isn’t a part of any of the legends of Auriga from Greek or Roman mythology. It may represent the goat that suckled the infant Zeus, who placed her and her children in the sky in gratitude. The goat and kids may once have formed their own small constellation. Today, though, they ride on the shoulder of the charioteer – who rides on nothing at all. More about the charioteer tomorrow. Script by Damond Benningfield

At the cusp of the 20th century, it seemed like contact with another world was just a matter of time. In fact, the French Academy of Sciences announced a prize for such a feat 125 years ago today. The winner would receive 100,000 francs. There was only one catch: Mars didn’t count. The prize was established by Clara Guzman in honor of her son. He was a follower of astronomer Camille Flammarion, who wrote extensively – and fancifully – about the Red Planet. Guzman excluded Mars from the competition because it seemed just too easy. Percival Lowell had popularized the idea that Mars was crisscrossed by canals – built by Martians to bring water from the poles to the planet’s deserts. Inventor Nicola Tesla had reported hearing possible radio signals from Mars. And many others thought that vast dark areas on Mars were covered with vegetation. Many schemes were proposed to contact the Martians. One suggested creating giant geometric shapes in Siberia. Another suggested digging the shapes into the Sahara Desert, filling them with kerosene, and setting them on fire. None of the schemes ever materialized. And no one ever claimed the prize for contacting another world. So the French academy decided to award the prize for making physical contact. In 1969, it awarded the Guzman Prize to Apollo 11 astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins – the first men to set foot on another world. Script by Damond Benningfield

The planet Mercury is shrinking. It’s contracted by several miles since its birth. And it’s continuing to get smaller even now. Mercury is the closest planet to the Sun. It’s also the smallest major planet in the solar system – a little more than 3,000 miles in diameter – about the width of the 48 states. It has a core of iron and nickel, surrounded by dense layers of rock. And it’s topped by a thin crust. The surface of the planet is marked by lots of impressive cliffs. The biggest is more than 600 miles long and about two miles high. They formed as Mercury lost heat from its interior. As the planet cooled, it shrank. Estimates of how much it’s contracted have ranged from about a mile to about nine miles. A recent study narrowed the range a little bit. It measured the most dramatic features, then scaled that to the surface of the entire planet. The result suggests that Mercury has shrunk by about three to five miles as a result of its cooling. And when you add in some other causes, the total contraction is about four to seven miles. And Mercury is still getting smaller today. This incredible shrinking planet is quite low in the southeast in the dawn twilight for the next few days. It looks like a bright star, but you need a clear horizon to spot it. And because of the viewing angle, it’s easier to spot from more southern latitudes. Tomorrow, the Moon stands to its right or upper right. Script by Damond Benningfield

Here’s what we know for sure about the planet K2-18b. It’s about 125 light-years away. It’s bigger and heavier than Earth. It orbits a cool, faint star once every 33 days. It receives about the same amount of energy from its star as Earth gets from the Sun. And it has an atmosphere. After that, things get muddled. Astronomers aren’t sure about the structure of the planet or the make-up of its atmosphere. And ideas about whether it might be habitable are all over the place. The confusion highlights the challenges of studying planets in other star systems. K2-18b passes in front of its star on every orbit. And as it does so, the chemical “fingerprints” of its atmosphere are added to the starlight. Substracting the starlight provides a profile of the atmosphere. But the profile is hard to read. Many of the fingerprints are subtle, and can be produced by different compounds. Earlier this year, a team announced the discovery of compounds in the atmosphere that could be produced by microscopic life. Follow-up studies by other groups contradicted that finding. But the original study team has stuck by its conclusions. So it’ll take a lot more work to know for sure what’s going on at K2-18b. The K2-18 system is in Leo, which climbs into good view after midnight. K2-18 is to the right of Denebola, the star that marks the lion’s tail. But it’s too faint to see without a telescope. Script by Damond Benningfield

For stars that are similar to the Sun, the end comes in stages. And each stage is triggered by changes in the star’s core. One star that’s going through those changes is Diphda, the brightest star of Cetus, the sea monster. The star is several hundred million years old – billions of years younger than the Sun. For most of its life, it “fused” hydrogen atoms in its core to make helium. When the hydrogen was gone, it began fusing hydrogen in a shell around the core. That made the star puff up, so it was classified as a red giant. Now, it’s finished off the shell, so it’s fusing the helium in the core to make carbon and oxygen. This phase is generally lumped into the red-giant category. Technically, though, it has its own name: the red clump. In a hundred million years or so, Diphda will have used up all the helium. The star isn’t massive enough to fuse the carbon and oxygen to make heavier elements. Without that energy, the core will collapse to about the size of Earth. It’ll be extremely hot, though, so it’ll blow away Diphda’s outer layers. For a while, the star will enter one more phase: a planetary nebula – a colorful cloud of gas and dust. When the cloud disperses, only the dead core will remain: a white dwarf – the hot but tiny remnant of a star. Cetus spreads across the southeastern quadrant of the sky at nightfall. Diphda is near its lower right corner, roughly a third of the way up the sky. Script by Damond Benningfield

People collect all kinds of things, from baseball cards to Persian rugs. Over the past 40 years, some NASA aircraft have collected dust – grains of dust from beyond Earth. Many of the collection efforts have taken place during meteor showers. That’s included the Geminid shower, which is at its peak tonight. A meteor shower takes place when Earth flies through a trail of particles that were shed by a comet or asteroid. Many of the particles burn up in the upper atmosphere, creating the streaks of light known as meteors. But many more grains are too small to burn up. They float down through the atmosphere. Some of them stop at a height of about 10 miles. And that’s where the research aircraft head. Once there, they open up small boxes that catch whatever is drifting along – pollen grains, parts of bugs, bits of volcanic ash, and even exhaust from rocket engines. Analysis reveals whether the captured particles are from Earth or from outside. The cosmic particles can then be tied to the meteor shower that was under way. And that can tell scientists about the shower’s parent body – a sample-return mission that never leaves Earth. The Geminids are in good view tonight. The meteors are visible from mid-evening on. At its best, the shower might produce a hundred or so meteors per hour. And you don’t need to look in a particular direction to see them – just look up and wait for the fireworks. Script by Damond Benningfield

A couple of thousand years ago, a large asteroid or comet might have been blasted apart. And we’re still seeing the fireworks from its destruction – as the Geminid meteor shower, which will reach its peak tomorrow night. Most meteor showers flare to life when Earth passes through the orbital path of a comet. The comet sheds bits of rock and dirt, which spread out along its orbit. As Earth flies through this trail of debris, the solid grains ram into the atmosphere, forming the glowing streaks known as meteors. But the Geminids are a bit odd. For one thing, their parent body – 3200 Phaethon – appears to be an asteroid or a “dead” comet, not an active comet. For another, the meteor stream contains way more material than we’d expect to see from a body the size of Phaethon. A couple of years ago, scientists came up with a possible explanation. They used observations by a Sun-orbiting spacecraft that passed through the meteor stream. They then used computer models to calculate a possible cause for the stream. They concluded that a larger body could have been destroyed. That produced Phaethon and a couple of other large remnants. But it also produced a giant cloud of dust and pebbles. So while some of the material that makes up the Geminids comes from Phaethon, a lot of it also comes from that cloud – shrapnel that makes fireworks in Earth’s night sky. More about the Geminids tomorrow. Script by Damond Benningfield

The Sun isn’t easy to influence. It’s more than a thousand times the mass of Jupiter, the solar system’s largest planet, and more than 330,000 times the mass of Earth. Even so, a recent study says the planets might influence our star’s magnetic cycle – perhaps making conditions more comfortable for life. The Sun goes through many cycles of magnetic activity. The best known lasts an average of 11 years. At the cycle’s peak, the Sun is much more active than average. It pelts Earth and the other planets with higher levels of radiation and charged particles. That can wreak havoc with everything from satellites to blood pressure. Another cycle lasts an average of less than two years. It produces “mini” peaks and valleys in the 11-year cycle. And it lines up well with the longer cycle. In the recent study, researchers from Germany compared these cycles to the orbits of the planets. They found that the peaks and valleys of the shorter cycle correspond to some planetary alignments. One was a lineup of Earth, Jupiter, and Venus. The other was an alignment of Jupiter and Saturn. The researchers said the planets may help control the solar cycles. The planets might even tamp down the Sun’s activity, which is weaker than that of many Sun-like stars. Less activity means that Earth gets bombarded by less of the nasty stuff – making our planet a much more comfortable home for life. Tomorrow: cosmic shrapnel. Script by Damond Benningfield

Storms on the Sun can cause all kinds of problems. They can knock out satellites and black out power grids. They can interfere with GPS and disrupt some radio broadcasts. They can even have an impact on human health. Solar storms happen when the Sun’s magnetic field gets tangled up. Lines of magnetic force can snap, then reconnect. That produces outbursts of radiation and charged particles. When the particles hit Earth, they’re funneled toward the surface by our planet’s own magnetic field. And that’s what causes the problems. Among the health concerns, particles and radiation can penetrate deeper into the atmosphere around the magnetic poles. That zaps anyone who’s flying at high altitudes in those regions. It’s not a fatal dose, but it’s enough to cause concerns. So airlines divert flights to avoid exposing passengers and crew. There’s also evidence that these bouts of “space weather” can boost people’s blood pressure. In one study, researchers in China looked at half a million blood pressure readings taken over six years. And they found a definite jump around the time of solar storms – especially among women and those with hypertension. An American team found similar results among older men. There’s no consensus about how space weather might cause blood pressure to spike. For now, all we know is that stormy skies on the Sun can cause lots of problems for the people on Earth. Script by Damond Benningfield

The Moon and the heart of the lion just miss each other tonight – at least as seen from the United States. As they climb into good view, after midnight, the Moon and the star Regulus will be separated by just a skosh. The farther north and east your location, the closer together they’ll appear. From some spots, they’ll be almost touching. And from much of Canada across to northern Norway they will touch – the Moon will occult the star. It’ll pass directly in front of Regulus, blocking it from view. The Moon can occult Regulus because the star lies almost atop the ecliptic – the Sun’s path across the sky. The Moon stays close to the ecliptic as well, but it does move a few degrees to either side. As a result, occultations of Regulus come in groups. This one is part of a cycle of that began earlier this year and will continue through the end of next year. Each occultation is visible from a different part of Earth. In part, that’s because each one lasts only a few minutes to a few hours, so the Moon and Regulus are below the horizon as seen from much of the world. Also, the Moon is so close to us that there’s a big difference in the viewing angle across the globe – up to two degrees – four times the width of the Moon itself. From any specific location, sometimes the angle is just right, but more often it’s a little off – providing a beautiful close encounter between the Moon and the heart of the lion. Script by Damond Benningfield

A couple of years ago, a space telescope discovered something odd about NGC 6505. The galaxy is encircled by a ring. It isn’t part of the galaxy itself. Instead, it’s an image of a background galaxy – one that’s billions of light-years farther. Einstein Rings are named for Albert Einstein because they were predicted by his theory of gravity. The gravity of a foreground object acts as a lens – it bends and magnifies the light of a background object. On small scales, gravitational lenses have revealed everything from black holes to rogue planets. Galaxies are much bigger and heavier, so they produce more dramatic lenses. Many of them create bright arcs. But when the alignment is just right, they can create a full circle. NGC 6505 is a good example. The galaxy is about twice the diameter of the Milky Way, and several times its mass. It’s about 600 million light-years away. The background galaxy is four billion light-years farther. The lensing effect has allowed astronomers to measure the amount of dark matter in the center of NGC 6505, as well as details about its stars – discoveries made possible by its beautiful ring. NGC 6505 is enwrapped in the coils of Draco, the dragon. The galaxy is more than a third of the way up the northwestern sky at nightfall. It’s visible through a small telescope. But you need a big telescope and a long exposure to make out its ring. Script by Damond Benningfield

The Moon is a “dead” world. It trembles with a few small moonquakes, and there may be occasional “burps” of gas. But for the most part, not much happens inside it. That’s definitely not the case for one of the moons of the giant planet Jupiter. Io is the most volcanically active world in the solar system. It’s covered by hundreds of volcanoes and pools of hot lava. Some of the volcanoes are larger than anything on Earth, and the lava is much hotter. The volcanoes can send gas and ash hundreds of miles high. Some of this material escapes Io completely – about one ton every second. It forms a wide “doughnut” around Jupiter. The activity is powered by a gravitational tug-of-war between Jupiter and some of its other big moons. They pull on Io in different directions. That heats Io’s interior, melting some of its rocks. A couple of recent studies found that Io has been at least this active since it was born. That suggests that Io and the other big moons have been locked into their current configuration since shortly after the birth of Jupiter itself. If that’s the case, then Io has been caught in a terrific tug-of-war for four and a half billion years. Jupiter rises above our moon this evening. The planet looks like a brilliant star – only the Moon and Venus outshine it. But you need binoculars to pick out Io and the planet’s other big moons. Tomorrow: gravitational “rings” around a galaxy. Script by Damond Benningfield

The Moon forms a beautiful grouping with the planet Jupiter and the twins of Gemini tonight. Jupiter looks like a brilliant star. It’s below the Moon as they climb into view, by about 8:30. Castor, the fainter of Gemini’s twins, is to the left of the Moon. And Pollux, the brighter twin, is to the lower left. The grouping is even tighter at first light tomorrow. The Moon circles through Gemini roughly once a month – the time it takes to complete one full turn through the background of stars. If you made a movie of those passages over the years, the Moon would look like a car that can’t stay in the same lane. That’s because the Moon’s orbit around Earth is tilted a bit compared to the ecliptic – the Sun’s path across the sky. So the Moon moves back and forth across the ecliptic during its month-long cycle. It moves from about five degrees north of it, to about five degrees south. The Moon’s position on the ecliptic relative to an individual constellation doesn’t change much from month to month. Instead, it takes years to see much of a difference. In the case of Gemini, that means that every few years the Moon comes especially close to Pollux. But then it moves away, and eventually leaves a big gap – up to the width of your fist held at arm’s length. But that won’t happen again until the early 2030s, as the Moon weaves into another lane. More about the Moon and Jupiter tomorrow. Script by Damond Benningfield

For radio astronomers, there’s some good news and some bad news. On the good side, a pilot project with SpaceX has devised a way to reduce the radio interference produced by satellites. On the bad side, the satellites can produce accidental interference. Radio telescopes tell us things about the universe that we can’t get any other way. But the telescopes are extremely sensitive. Transmissions from an orbiting satellite are like bright headlights – they overpower the subtle signals of astronomical objects. There are more than 15,000 satellites in orbit today – a five-fold increase in just six years. And the total could balloon to a hundred thousand by the next decade. Astronomers worked with SpaceX to reduce interference from its Starlink satellites. The groups combined the observing schedule of a telescope with the Starlink control system. Satellites passing over the telescope were instructed to turn away – aiming the headlights in a different direction. And there are plans to extend the scheme to other telescopes. On the other hand, a recent study found that tiny radio signals emitted by a satellite’s electronics can also be a problem. Scientists looked at 76 million radio images made by a telescope in Australia. They found that Starlink satellites interfered with up to 30 percent of the pictures. So future satellites may need extra shielding to keep them from blinding astronomy’s radio eyes. Script by Damond Benningfield

Most of the stars are so small and far away that they’re nothing more than pinpoints even in the largest telescopes. That makes it impossible to measure the size of a star. But astronomers can measure the sizes of some stars – not with a giant telescope, but with a collection of smaller ones. The technique is called interferometry. It links up several telescopes. The combo provides an especially sharp view of the heavens. If the telescopes are, say, 300 feet apart, then the combined view is as clear as that of a single telescope 300 feet in diameter. The array’s view isn’t as deep as that of a giant telescope, only as sharp. Interferometers have allowed astronomers to measure the apparent sizes of hundreds of stars. Combining that with a star’s distance provides its true size. One example is Elnath, the second-brightest star of Taurus. It’s about 134 light-years away. It’s five times the mass of the Sun. So even though it’s much younger than the Sun, it’s already passed through the prime phase of life. That’s caused it to puff up – to almost five times the Sun’s diameter. At that size, it shines more than 800 times brighter than the Sun – a big beacon for the bull. Elnath is close to the lower left of the Moon this evening. The Moon will move toward the star during the night. They’ll be closest at dawn. The gap will be smaller for skywatchers on the West Coast, and smallest for those in Alaska and Hawaii. Script by Damond Benningfield

[3, 2, 1, ignition, and liftoff of SOHO and the Atlas vehicle on an international mission of solar physics.] Generally speaking, staring at the Sun non-stop for decades is a bad idea. But a spacecraft launched 30 years ago this week has done just that. It’s told us about the Sun’s interior, its surface, and its extended outer atmosphere. That’s helped scientists develop better forecasts of space weather – interactions between Sun and Earth that can have a big effect on our technology. The craft is called SOHO – Solar and Heliospheric Observatory. It was launched into an orbit around a point in space where the gravity of Earth and the Sun are balanced. From there, its view of the Sun is never blocked. SOHO watches the Sun in many different ways. It keeps a close eye on the Sun’s magnetic field, which produces outbursts of energy and particles that can have an impact on Earth. That’s revealed shockwaves and “tornadoes” rippling across the Sun’s surface. It’s also revealed the source of the solar wind – a steady flow of charged particles that blows through the solar system. Some of SOHO’s observations block out the Sun itself, showing the space around the Sun. That’s allowed SOHO to discover more than 5,000 comets as they passed close to the Sun – many of which didn’t survive. SOHO’s mission is scheduled to end soon – closing this long-working eye on the Sun. Script by Damond Benningfield

Scientists have been searching for dark matter for decades. They haven’t found it – every experiment they’ve devised has come up empty. But they haven’t given up. Among other ideas, they’re thinking about ways to use moons, planets, and stars as detectors. Dark matter appears to make up about 85 percent of all the matter in the universe. We know it’s there because its gravity pulls on the visible stars and galaxies around it. Dark matter may consist of a type of particle that almost never interacts with normal matter. But it should interact just enough to reveal its nature. Experiments here on Earth haven’t seen any such interactions. So some scientists recommend using astronomical objects instead of lab experiments. Blobs of dark matter might enfold a binary star system. The dark matter’s gravity could pull the two stars away from each other. And dark matter might clump together to make a special kind of star. Both of those might be detectable with current telescopes. Smaller blobs might slam into an icy moon, creating a special kind of crater. Such craters could be visible on Ganymede, the largest moon of Jupiter. Two missions on their way to Jupiter might be able to see them. And dark matter might fall into the center of a planet and hang around. If enough builds up, it could heat the planet’s interior. So by studying many planets in other star systems, we might see some that are unusually warm – heated up by encounters with dark matter. Script by Damond Benningfield

Things are heating up for a planet that orbits the brightest star of Aries. The star is expanding to become a giant, so it’s pumping more energy into space. That will make temperatures extremely uncomfortable on the planet. Hamal is at the end of its life. It’s converted the hydrogen in its core to helium. Now, it’s getting ready to fuse the helium to make other elements. That’s made the core hotter. And that’s caused the star’s outer layers to puff up – to more than a dozen times the diameter of the Sun. So Hamal is about 75 times brighter than the Sun. Hamal has one known possible planet. It’s heavier than Jupiter, the giant of our own solar system. On average, the planet is about as far from Hamal as Earth is from the Sun – much closer in than Jupiter is. So every square foot of the planet’s surface receives dozens of times more energy than the same area on Jupiter does. If the planet is a ball of gas like Jupiter, then the extra heat is causing its atmosphere to puff up – and causing a lot of it to stream away into space. Over the next few million years, the planet will get even hotter, because Hamal will get even bigger. The extra energy may erode the planet’s atmosphere completely. On the other hand, the planet may spiral into the star. Either way, things are going to get much hotter for Hamal’s only known planet. Look for Hamal in the east at nightfall, well to the left of the Moon. Script by Damond Benningfield

As most parents can tell you, coming up with names isn’t easy. It sometimes takes a while to settle on something that sounds just right. It wasn’t easy for the people who named the constellations, either. Some of the names sound like they just gave up. They picked a region of the sky with few stars, gave it the name of a nearby bright constellation, then added the word “minor.” All three of these minor constellations are in good view at dawn: Ursa Minor, Canis Minor, and Leo Minor. The most famous of the bunch is Ursa Minor – the little bear. Seven of its stars form the Little Dipper, which is in the north – directly below the Big Dipper, which is part of Ursa Major. The constellation is especially well known because its brightest star is Polaris, the Pole Star. It’s at the tip of the little bear’s tail. Canis Minor is the little dog. It’s about half way up the sky in the west-southwest. It has only a couple of bright stars. The brightest is Procyon – a name that means “before the dog.” That’s because the little dog leads the big dog across the sky. In ancient Greece, in fact, the constellation was known as Procyon. Finally, Leo Minor is high overhead. It’s the little lion, standing on the shoulder of Leo. That region of the sky wasn’t depicted as a separate constellation until 1687. Today, though, it’s one of the 88 official constellations – even if it is a “minor” one. Script by Damond Benningfield

The shortest season on the planet Mars begins today – autumn in the northern hemisphere, and spring in the southern hemisphere. It will last for 142 Mars days – almost eight weeks less than the longest season. Mars has seasons for the same reason that Earth does – it’s tilted on its axis. And the tilt is at almost the same angle as Earth’s. But the seasons on Mars are more exaggerated because the planet’s orbit is more lopsided. A planet moves fastest when it’s closest to the Sun, and slowest when it’s farthest from the Sun. That stretches out some seasons, and compresses others. It also changes the intensity of the seasons. Mars is farthest from the Sun when it’s summer in the northern hemisphere. So northern summers are fairly mild, while southern winters are bitterly cold. On the flip side of that, northern winters are less severe, while southern summers are the warmest time on the whole planet. The start of northern autumn also marks the beginning of dust-storm season. Rising currents of air can carry along grains of dust. Enough dust can be carried aloft to form storms that cover thousands of square miles. And every few Martian years, a storm gets big enough to cover the entire planet. The storms usually peak around the start of southern summer. Mars is about to pass behind the Sun, so it’s hidden in the Sun’s glare. It’ll return to view, in the dawn sky, in early spring – on Earth. Script by Damond Benningfield

The Moon slides by Saturn the next couple of nights. The planet looks like a bright star. It’s to the left of the Moon as night falls this evening, and to the lower right of the Moon tomorrow night. Saturn is best known for its rings. They’re almost wide enough to span the distance from Earth to the Moon. Right now, we’re viewing them almost edge-on, so they look like a thin line across the planet’s disk. Saturn isn’t the only world with rings. The solar system’s three other giant outer planets also have them. But they’re dark and thin, so they’re hard to see. Several asteroids and dwarf planets have rings, too. But the biggest set of rings yet seen may encircle a “rogue” planet about 450 light-years away. The possible rings were discovered years ago. Over a period of eight weeks, the light of a star in Centaurus flickered – sometimes dropping to just five percent of its normal level. The most likely cause was the passage of a set of rings in front of the star. And it’s quite a set. The rings are more than a hundred million miles across – greater than the distance from Earth to the Sun. The ringed planet appears to be traveling through the galaxy alone, and it just happened to pass in front of the star. It could be up to six times the mass of Jupiter, the giant of our own solar system. And moons could be orbiting inside the rings – the most impressive rings we’ve seen anywhere in the galaxy. Script by Damond Benningfield

Planets are tough little buggers. They can form and survive in some extreme environments. In fact, the first confirmed planets outside our own solar system orbit the remnant of a dead star – a pulsar. A pulsar is tiny – the size of a small city. But it’s more massive than the Sun. A teaspoon of its matter would weigh as much as a mountain. Yet a pulsar spins rapidly – up to several hundred times per second. It has an extreme magnetic field. The field shoots “jets” of particles out into space. As the pulsar spins, the jets can sweep across Earth like a lighthouse beacon, producing short pulses of energy. The timing of those pulses is extremely precise. That makes pulsars some of the best clocks in the universe. But the timing can be changed by a companion – another star, or even a planet. And that’s how pulsar planets are discovered – through tiny changes in the timing of the pulses. Eight pulsar planets have been confirmed. But they present quite a challenge. A pulsar is the remnant of a titanic explosion – a supernova. It’s hard to see how any planets could survive such a blast. So it’s likely that the planets formed after the blast – perhaps from debris from the explosion’s aftermath. Regardless of how they formed, the planets aren’t friendly places. They’re blasted with charged particles, X-rays, and gamma rays from the pulsar. That may slowly erode the planets – no matter how tough they are. Script by Damond Benningfield

[pulsar audio] This is the rhythm of the stars – the beat of dead stars. It’s the “pulses” of radio waves produced by rapidly spinning stellar corpses. They produce beams of energy that sweep around like the beacon of a lighthouse. Radio telescopes detect the beams when they sweep across Earth. The stars are known as pulsars. They’re some of the most extreme objects in the universe. They’re neutron stars – the dead cores of some of the most massive stars. When a heavy star can no longer produce nuclear reactions in its core, the core collapses. Gravity squeezes the core down to the size of a small city. But that tiny ball is heavier than the Sun. The star is rotating as it dies. As the core collapses, it keeps on spinning. But the smaller it gets, the faster it spins. So newborn neutron stars can spin a few dozen to a few hundred times per second. Particles trapped in the neutron star’s magnetic field produce energy that’s beamed into space – the source of the pulses. The neutron star spins down over time, slowing the pulses. But if it has a close companion, it can be revved up even faster. The neutron star can pull gas from the surface of the companion. As it hits the neutron star, the gas acts like an accelerator – creating some of the fastest pulsars in the universe. These extreme stars can still host planets; more about that tomorrow. Script by Damond Benningfield

Getting too close to a black hole is bad news. The black hole’s gravity can pull apart anything that’s falling into it atom by atom. A magnetar can do the same thing. And it’s not just its gravity you have to worry about. Its magnetic field can do the job as well – from hundreds of miles away. A magnetar is a neutron star -the crushed corpse of a once mighty star. It’s heavier than the Sun, but only a little bigger than Washington, D.C. It’s born when a massive star can no longer produce nuclear reactions in its core. The core collapses, while the star’s outer layers explode. The original star generated a strong magnetic field. As the core collapsed, the field was mashed inward as well, making it extremely powerful. It’s boosted by the turbulent sloshing inside the newly formed neutron star. So a typical magnetar’s magnetic field is a million billion times the strength of Earth’s field. The neutron star sticks around, but its magnetic field weakens in a hurry. So there aren’t many magnetars around – only about 30 have been discovered. The magnetic field can help produce titanic explosions. Interactions with the field can cause the crust of a neutron star to crack in a “starquake.” Energy from the quake is beamed out by the magnetic field, producing an outburst of gamma rays. The most powerful quake yet seen generated more energy in a tenth of a second than the Sun will emit in 150,000 years – the enormous power of a magnetar. More about neutron stars tomorrow. Script by Damond Benningfield

When the most massive stars die, they can leave behind two types of corpse. The heaviest ones probably form black holes. But the fate of the others is no less exotic. They form neutron stars – ultra-dense balls that are more massive than the Sun, but no bigger than a small city. A massive star “dies” when its core can no longer produce nuclear reactions. For a star of about eight to 20 or more times the mass of the Sun, the core collapses, while the star’s outer layers explode as a supernova. The gravity of the collapsing core squishes together protons and electrons to make neutrons – particles with no electric charge. The neutrons can be squished together only so much before they halt the collapse. By then, the core is trillions of times as dense as Earth. So a chunk of a neutron star the size of a sugar cube would weigh as much as a mountain. A neutron star probably has a solid crust made of iron or other elements, with no features more than a couple of millimeters tall. The gravity at the center of a neutron star is so strong that we don’t really know what the conditions are like – there’s just nothing to compare it to. There could be as many as a billion neutron stars in the galaxy. But they’re hard to find. Some of them make it a little easier, though. They produce the most powerful magnetic fields in the universe – and some of the most powerful outbursts. More about that tomorrow. Script by Damond Benningfield

You can always count on the constellations. Over the course of a human lifetime, their configuration doesn’t change – they don’t appear to move at all. That’s an illusion, though. The stars are all so far away that we don’t see any motion. But they’re all moving in a hurry. And one of the fastest is in view on autumn evenings. Gamma Piscium is the second-brightest member of Pisces, the fishes. The constellation stretches across the east and southeast at nightfall. Gamma Piscium is near its top right corner – part of a pentagon of faint stars. Gamma Piscium is a giant. It’s nearing the end of its life, so it’s getting bigger and brighter. Right now, it’s about 10 times the diameter of the Sun, and more than 60 times the Sun’s brightness. That makes it faintly visible to the eye alone, even though it’s 135 light-years away. Perhaps the most interesting fact about Gamma Piscium is its speed: It’s moving through the galaxy at about 340,000 miles per hour – faster than all but a few other visible stars. At that rate, it’ll move the equivalent of the Moon’s diameter in less than 3,000 years. The star’s composition hints that it came from outside the disk of the Milky Way – the part of the galaxy that includes the Sun. The star has very few heavy elements. That suggests it formed outside the disk, and just happens to be passing by – zipping through the galaxy like a speeding rocket. Script by Damond Benningfield

An interloper from another galaxy scoots low across the south on October evenings. It’s a tight family of stars – hundreds of thousands of them. The stars probably belonged to another galaxy that was consumed by the Milky Way in the distant past. Messier 30 is low in the south at nightfall, in Capricornus. The sea-goat’s brightest stars form a wide triangle. M30 is on the lower left side of the triangle Messier 30 is a globular cluster – a ball of stars about 90 light-years wide. Most of the stars are concentrated in the cluster’s dense core. The numbers tail off as you move toward the cluster’s edge. Anything that wanders too far from the center gets yanked away by the gravity of the rest of the galaxy. The Milky Way is home to more than 150 globular clusters. But several of them appear to have come from other galaxies. And that includes M30. The main clue to its origin is its orbit. As it circles the center of the galaxy, M30 moves in the opposite direction from most of the stars and star clusters. The only way for such a massive cluster to move against the traffic is if it came from outside the galaxy. So Messier 30 isn’t a native of the Milky Way. Instead, it was pulled in by the Milky Way’s powerful gravity – making it a refugee from another galaxy. We’ll talk about an individual star that might be a refugee from another part of the galaxy tomorrow. Script by Damond Benningfield

If you’ve ever left a can of soda in the freezer for too long, you can appreciate what happened to the largest moon of the planet Uranus: It cracked. Titania is almost a thousand miles in diameter – less than half the size of our moon. But it orbits Uranus at about the same distance as the Moon does from Earth. And like the Moon, it’s locked in such a way that the same hemisphere always faces its planet. When Titania was born, its interior was warm. But it quickly froze. As it did so, the surface cracked, creating some impressive canyons. The largest is a network known as Messina Chasma. Like Titania itself, it’s named for a character from Shakespeare – in this case, from “A Midsummer Night’s Dream`.” The canyons are more than 900 miles long, wrapping from the equator to near the south pole. They’re up to 60 miles wide, and miles deep. Few impact craters have scarred Messina, indicating that it’s fairly young. In fact, Titania’s entire surface appears to be younger than those of Uranus’s other big moons. That doesn’t mean the moon itself is younger. Instead, it probably was repaved by ice flowing from inside – resetting the clock for this fractured moon. Uranus is in view all night, in Taurus. And it’s closest to Earth for the year – 1.7 billion miles away. Despite the distance, it’s big enough that it’s an easy target for binoculars. But you need a decent telescope to see Titania. Script by Damond Benningfield

Uranus is the seventh planet of the solar system, so it’s a long way from both the Sun and Earth. Right now, it’s about 1.7 billion miles away. At that distance, under especially dark skies it’s barely bright enough to see with the eye alone. It’s easy to pick out with binoculars, though. This is an especially good week to look for the planet because it reaches opposition, when it lines up opposite the Sun. It rises around sunset and is in view all night. And it shines brightest for the entire year. In early evening, it’s close to the lower right of another good binocular target, the Pleiades star cluster. Even though Uranus is sometimes visible to the eye alone, it’s so faint that no one realized it was planet for a long time. Every astronomer who saw Uranus logged it as a star, missing out on a chance at immortality. It was officially discovered as a planet by British astronomer William Herschel, in 1781. But even he was fooled by it for a while. When he first saw it, he thought it was a comet. But calculations of its orbit showed that the object was much too far away to be a comet – it had to be a planet, and a big one. Herschel wanted to call it George’s Star after his patron, King George III. Astronomers outside Britain weren’t crazy about that. So almost 70 years later, they finally named it for a Greek god of the sky: Uranus. More about Uranus tomorrow. Script by Damond Benningfield

A barely-there crescent Moon teams up with the disappearing “morning star” in tomorrow’s dawn twilight. But there’s not much time to look for them. The Moon will cross between Earth and the Sun in a couple of days. It’ll be lost in the Sun’s glare. It will return to view, in the evening sky, by Friday or Saturday. Venus is getting ready to disappear in the dawn twilight as well. It will cross behind the Sun on January 6th. It’s a slower passage, so the planet will be hidden in the Sun’s glare for about three months. It’ll emerge as the “evening star” in February. Most cultures figured out that the morning and evening star were actually the same object thousands of years ago. Even so, they had different names for the morning and evening appearances. In ancient Greece, morning Venus was named for the god Phosphorus. In Rome, he was Lucifer. Both names mean “bringer of light” – the god lit the dawn sky with a torch. Venus passes behind the Sun every 584 days – a bit more than 19 months. Before and after it disappears, it’s almost full. So if you look at Venus with a telescope now, it’ll be almost fully lit up – like a negative image of the “fingernail” crescent Moon. Look for Venus and the Moon quite low in the eastern sky beginning about 45 minutes before sunrise. Because of the timing and the viewing angle, they’ll be a little easier to spot from the southeastern corner of the country. Script by Damond Benningfield

If you ever warp over to another star, it would help to know its distance. Say, for example, you wanted to visit Spica, the brightest star of Virgo, which is quite close to the Moon at dawn tomorrow. The system is worth visiting because it consists of two giant stars. They’re so close together that their shapes are distorted, so they look like eggs. The best measurement we have says that Spica is 250 light-years away. But there’s a margin of error of about `four percent. So you could undershoot or overshoot the system by 10 light-years. The distances of most stars are measured with a technique called parallax. Astronomers plot a star’s position at six-month intervals, when Earth is on opposite sides of the Sun. That can produce a tiny shift in the star’s position against the background of more-distant objects. The bigger the shift, the closer the star. But the stars are so far away that the shift is tiny – like the size of a dime seen from miles away – or hundreds of miles. And Earth’s atmosphere blurs the view, so the stars look like fuzzy blobs instead of sharp points. So the most accurate measurements have been made from space. Spica’s distance was measured by Hipparchos, a European space telescope. An even more accurate satellite, Gaia, measured the distances to more than a billion stars – but not Spica. The star was too bright for its detectors – leaving a big margin of error for this impressive system. Script by Damond Benningfield

The patchiest of all meteor showers will be at its best tomorrow night. Unfortunately, this is one of its off years. At best, it might produce a dozen or so “shooting stars” per hour. Over the past two centuries, though, the Leonids have produced some amazing outbursts. The first of these came in 1833. Skywatchers in parts of America reported rates of a hundred thousand meteors per hour – not a shower, but a storm. The nature of meteor showers was unknown at the time, so many saw the outburst as the end of the world. The Leonids flare to life when Earth crosses the path of Comet Tempel-Tuttle. The comet passes close to the Sun every 33 years or so. It sheds tons of material on each pass – tiny bits of rock and dirt. Each cloud of debris spreads out and forms its own stream. A shower takes place when Earth flies through one of the streams. Newer streams are denser, so they produce more intense displays. Those streams congregate near the comet, so the outbursts occur when the comet is close to the Sun. The last outburst came in the early 2000s. And Earth probably won’t pass through another storm-producing stream until the end of the century – leaving us with meager displays of the Leonids. To see this year’s display, find a safe viewing site away from city lights. The meteors can appear anywhere in the sky, so you don’t need to look in a particular direction to see them. The best view comes between midnight and dawn. Script by Damond Benningfield

Galaxies frequently collide with each other, and the results can be spectacular. The encounters can pull out giant ribbons of stars. They can trigger intense bouts of starbirth. And they can scramble a galaxy’s stars and gas clouds, creating beautiful rings that look like cosmic bulls-eyes. One well-known galaxy that’s experienced a head-on collision is the Cartwheel. It’s about 500 million light-years away, in the constellation Sculptor, which is low in the south on November evenings. The Cartwheel is a good bit bigger than the Milky Way. It has a bright inner ring of mainly older stars that’s offset a little from the galaxy’s middle. A brighter ring of younger, bluer stars is far outside it. Wispy spiral arms that look like the spokes of a wagon wheel connect the rings, giving the “Cartwheel” its name. The Cartwheel probably started as a normal spiral galaxy. But a few hundred million years ago, a smaller galaxy plunged through it. The collision created a wave that rippled outward, like a rock thrown into a still pond. The wave disrupted the original spiral structure. It also squeezed clouds of gas and dust, causing them to give birth to new stars. And the drama isn’t over. Many more stars are being born in the outer ring, in giant nurseries that look like a strand of lights on a Christmas wreath. They will continue to make the Cartwheel shine brightly as it spins through the universe. Script by Damond Benningfield

Nicolas-Louis de Lacaille had a great imagination. In the 1750s, the French astronomer mapped more than 10,000 stars from the southern tip of Africa. Lacaille used those stars to create 14 new constellations. One of them is Sculptor. Lacaille originally called it the Sculptor’s Studio. It depicted a carved head atop a stool, plus a hammer and chisel and a block of granite. But all of that takes a lot of imagination to see. All of the constellation’s stars are so faint that Sculptor is invisible from light-polluted cities and suburbs. Sculptor is important to astronomers, though, because many galaxies lie within its borders. The closest of them is the Sculptor Dwarf. It’s just 300,000 light-years away, and it orbits our home galaxy, the Milky Way. The galaxy contains only 30 million stars or so. But most of them are ancient – far older than most of the stars in the Milky Way. That means the Sculptor Dwarf may be a remnant from the early universe – like the many building blocks that came together to form the Milky Way. So studying the galaxy can tell us much more about the early universe, and the history of our own galaxy. From most of the United States, Sculptor is low in the southeast in early evening,. But you need a dark sky to make out any of its stars – and a good imagination to “see” a pattern in them. We’ll have more about Sculptor tomorrow. Script by Damond Benningfield

The brightness of any star that’s in the prime phase of life is controlled by the star’s mass: Heavy stars are brighter than lightweight stars. But it’s not a simple one-to-one kind of relationship. A star that’s twice the mass of the Sun isn’t twice as bright – it’s more than 15 times as bright. That’s because gravity squeezes the core of a heavier star more tightly. That increases the core’s temperature, which revs up the rate of nuclear reactions. That produces more energy, which makes its way to the surface and shines out into space. Regulus illustrates the point. The heart of the lion consists of four stars, three of which are in the prime of life. The star we see as Regulus – Regulus A – is a little more than four times the mass of the Sun, yet it radiates about 340 times more energy. Much of that energy is in the ultraviolet, which we can’t see. But even at visible wavelengths, it’s about 150 times the Sun’s brightness. Regulus A has a couple of distant companions. Regulus B is about 80 percent the mass of the Sun, but only a third of the Sun’s total brightness. And Regulus C is even more dramatic: a third of the Sun’s mass, but just two percent its brightness – a cool, faint ember in the heart of the lion. Look for Regulus standing close above the Moon as they climb into good view around 1:30 or 2 in the morning. The star will be a little farther from the Moon at dawn. Script by Damond Benningfield

Edwin Hubble gets the credit for discovering that the universe is expanding. But that finding was made possible by work done by Vesto Slipher. He was the first to measure the motions of distant galaxies – the key to Hubble’s discovery. Slipher was born 150 years ago today, in Mulberry, Indiana. He worked on the family farm, and developed an interest in astronomy. A college professor helped him get a job as an assistant at Lowell Observatory in Arizona, where he worked for the next five decades. Slipher studied what were called “spiral nebulae.” It wasn’t certain whether these pinwheels were motes of matter in the Milky Way, or “island universes” of stars outside the Milky Way. Slipher used a technique that splits an object’s light into its individual wavelengths. The object’s motion shifts those wavelengths. Objects that are moving away from us are shifted to longer, redder wavelengths. Slipher found that most of the spirals were moving away from us in a hurry. He suggested the objects were far outside the Milky Way. But he couldn’t prove it because he had no way to measure the distances. Hubble did measure the distances, proving that the spirals are separate galaxies. He then combined Slipher’s observations with his own to show that the farther a galaxy, the faster it was moving. Later, astronomers concluded that the universe is expanding – a finding made possible in large part by Vesto Slipher. Script by Damond Benningfield

There’s nothing in the night sky quite like the Pleiades. The star cluster forms a tiny dipper. Depending on sky conditions and the viewer’s eyesight, anywhere from a half dozen to a dozen stars or more are visible to the naked eye. Its unique visage has made the Pleiades one of the most important sky objects in many cultures. The people of the Andes timed the start of the harvest season to its first appearance in the dawn sky. The Aztec year began at about the same time. In Hawaii, the Pleiades was known as Makali’i. And the year began when Makali’i first appeared in the evening twilight – the middle of November. The year, the new year, and a festival period shared a name: Makahiki. The customs varied from island to island. But they had a lot in common. The celebration lasted for several months. Warfare and most work were banned. Instead, people danced, feasted, played sports, and reconnected with family and friends. And they made offerings to Lono, a god of agriculture, music, and peace. The Pleiades is just climbing into the evening twilight, in the east-northeast, across Hawaii and most of the rest of the country. In some Hawaiian traditions, Makahiki doesn’t begin until the first appearance of the crescent Moon in the west after the Pleiades returns. That’s coming up on the 21st – the start of the new year and the celebration that honors it. Hau’oli makahiki hou! – Happy New Year! Script by Damond Benningfield

The Moon shoots the gap between some bright companions tonight: the planet Jupiter and the star Pollux, the brighter “twin” of Gemini. They climb into good view by about 10:30 or 11, and stand high overhead at dawn tomorrow. Jupiter is the largest planet in the solar system, and it has the most turbulent atmosphere. Hurricane-like storms as big as continents twirl across it. Thunderstorms can produce lightning bolts far more powerful than any on Earth, as recorded by a passing spacecraft. And the storms might produce their own giant hailstones: “mushballs” as big as softballs. The idea was first proposed in 2020. And a study published earlier this year supports it. The study used observations by the Juno spacecraft, which is orbiting Jupiter, along with Hubble Space Telescope and a radio telescope on Earth The study says the mushballs may begin as droplets of frozen water far below the cloud deck. They get caught in updrafts that howl at 200 miles an hour. They’re carried to the tops of the clouds, which can be tens of miles thick. Along the way, the ice mixes with ammonia, forming a slushy liquid. When the balls get heavy enough, they begin to drop. As they descend, they’re coated with fresh ice, giving them a hard shell around a slushy middle – mushballs. The mushballs plunge hundreds of miles below the clouds, where they vaporize – “mushing” into the depths of the giant planet. Script by Damond Benningfield

In the early 20th century, scientists discovered a mysterious new type of radiation. The higher they went, the stronger it became. They realized that it came from beyond Earth. And 100 years ago tomorrow, it got a name: cosmic rays. Nobel Prize winner Robert Millikan had become fascinated by the rays from outer space in the early ’20s. He coined the name “cosmic rays” in a paper about them, which he presented to a meeting on November 9th, 1925. Millikan thought the rays were a form of energy produced by matter that was being born in the space between the stars. Others disagreed, especially Arthur Compton – a future Nobel Prize winner himself. He argued they were subatomic particles racing through the universe at almost the speed of light. Compton was right. Cosmic rays are electrons, protons, or the nuclei of atoms. Most of the ones that hit Earth are produced by the Sun. But others come from far beyond our own solar system – and even from beyond our galaxy. The most energetic ones come from exploding stars, or from the violent regions around black holes. Most of these distant cosmic rays are blocked by the Sun or by Earth’s magnetic field. But a few enter the atmosphere. They strike atoms and molecules in the air, creating “showers” of other particles. If a shower occurs above the right kind of clouds, it can create lightning – a terrestrial light show with an extra-terrestrial origin. Script by Damond Benningfield

Nothing can survive the brutal conditions on the surface of the Moon. But a story that debuted 125 years ago depicted a vast civilization below the surface – a society of insects. First Men in the Moon was written by H.G. Wells. It was published over several months in two magazines – “The Cosmopolitan” in the United States, and “The Strand” in Britain. The first installment appeared in November of 1900. In the story, a man named Bedford befriends a scientist named Cavor who’s invented “cavorite” – a substance that nullifies gravity. He builds a ship and covers it with shutters that are coated in the stuff. Opening and closing the shutters allows the ship to move through space. The two men travel to the Moon, where they’re taken underground by the Selenites. Bedford escapes. Thinking Cavor is dead, he returns to Earth alone. But two years later, Cavor starts beaming messages to Earth. He describes the Moon and its inhabitants in detail. After he tells the Selenite’s leader of Earth’s war-like tendencies, though, he’s cut off – and never heard from again. First Men in the Moon was a hit. It influenced scientists and other fiction writers alike for decades, inspiring more stories, plus efforts to reach the Moon – a world populated only in the imagination. The Moon climbs into good view by about 8 o’clock tonight. Elnath – the second-brightest star of Taurus – is quite close to the Moon’s upper left. Script by Damond Benningfield

The black hole at the heart of the Milky Way is like the monster lurking under your bed. It’s four million times the mass of the Sun, and about 15 million miles across – just waiting to gobble up anything that gets too close. But compared to the black holes in many other galaxies, the one in the Milky Way is less like a monster and more like a dust bunny. The largest ones yet seen are thousands of times bigger. They’re known as ultra-massive black holes. Informally, they’re also called SLABs – stupendously large black holes. Just which one is the biggest is uncertain – it’s hard to measure the mass of something that might be billions of light-years away. A recent candidate is in a structure known as the Cosmic Horseshoe. The gravity of a stupendously large galaxy “warps” the view of a galaxy behind it, creating what looks like a big, blue horseshoe. In a recent study, astronomers combined a couple of techniques to measure the mass of the black hole in the foreground galaxy: 36 billion times the mass of the Sun. Researchers say the combo makes the measurement the most accurate for any candidate for the “biggest black hole” honors. But other black holes could be bigger. The biggest candidate is known as Phoenix A. It could be up to about 25 thousand times the mass of the Milky Way’s black hole. But that number is highly uncertain. So the search for the biggest black hole continues. Script by Damond Benningfield

A Little Red Dot might have a big black hole in its heart. And that’s a bit of a challenge to explain. Little Red Dots are galaxies from the first 1.5 billion years of the universe. The name comes from their appearance – they’re small and red, but they’re especially bright. They don’t appear to have enough stars to make them so bright. So a good bit of their “shininess” could come from giant black holes that are devouring material around them. As they tumble inward, the hot gas, dust, and stars produce enormous amounts of energy. Even so, the black hole in one Little Red Dot is a bit of a puzzler. Led by astronomers at the University of Texas at Austin, a team looked at CAPERS-LRD-z9 with Webb Space Telescope. By measuring the speed of material orbiting the center of the galaxy, the team determined that the black hole is up to 300 million times the mass of the Sun. And that’s where the challenge comes in. The galaxy is so far away that we see it as it looked when the universe was just 500 million years old – three percent of its current age. That makes the black hole the most-distant yet seen. But theories of how such monster black holes form say that half a billion years probably isn’t long enough to make one that big. So theorists have a lot of work to do to explain the giant black hole at the center of a Little Red Dot. More about black holes tomorrow. Script by Damond Benningfield

With the autumn harvest safely stowed away, many people in bygone centuries turned their attention to hunting. And just as the Harvest Moon helped them bring in the crops, the Hunter’s Moon helped them find game. The moonlight made it easier to track animals through the empty fields and beyond. Although most present-day Americans don’t have to worry about storing food for the winter, we still keep the names for those full Moons. We had the Harvest Moon last month. And tonight, it’s time for the Hunter’s Moon. The names for both of these full Moons come mainly from parts of Europe and the British Isles. The names were recorded as far back as the early 1700s, but they’d probably been in everyday use for much longer. Variations of the “Hunter’s Moon” label were used by several native tribes and nations in the Americas as well. The Harvest Moon is usually defined as the full Moon closest to the autumn equinox. Most years, that puts it in September. But this year, October’s full Moon edged out September by just a few hours. So the Hunter’s Moon got bumped into November. Officially, the Moon will be full at 7:19 a.m. Central Standard Time tomorrow. So it will appear almost as “full” when it rises tomorrow night as it does tonight – extra time to appreciate the brilliant glow of the Hunter’s Moon. Tomorrow: A giant black hole at the center of a little red dot. Script by Damond Benningfield

In 1908, a space rock the size of a small office building exploded above Siberia, flattening hundreds of square miles of forest. In 1975, several “fireballs” blazed across the night, and instruments on the Moon recorded several impacts. And 30 years later, scientists saw an impact on the Moon. These events might all be related to the Taurid meteor shower, which is underway now. The shower is created by two objects – a comet and an asteroid. They might be the remnants of a larger body that broke apart thousands of years ago. The debris might include larger rocks ranging from the size of boulders to mountains. The material is spaced across a long, wide path. Earth flies through this path twice a year. We sweep up some of the debris – mostly small bits of dust and rock. The amount of material varies from year to year, depending on which part of the stream we pass through. Right now, we’re in a thin region. In 1975, we passed through a denser part, producing more fireballs. It’s been suggested that when we pass through denser parts of the stream, we might encounter some of the bigger rocks, which could cause major damage if they hit us. Astronomers will be watching during the next crossings through dense regions, in the next decade. For now, the Taurids are at their best the next few nights. The Moon will wash out almost all the meteors. But a few fireballs might shine through. Script by Damond Benningfield

The Taurid meteor shower has a double identity. It’s split into two different streams, which peak a few nights apart in early November. Neither stream is particularly impressive, but things pick up when they overlap. Their story begins thousands of years ago, with the breakup of a big ball of ice and dust – Comet Encke. The biggest remaining chunk kept that name. But the breakup created several other big pieces, plus clouds of dust. The whole messy bunch is known as the Encke Complex. The southern Taurid stream consists of small bits of dust and rock shed by Encke itself. The northern stream is produced by one of its offspring – an asteroid that wasn’t discovered until 2004. Both streams contain a lot of debris, but it’s spread across tens of millions of miles. So it takes Earth weeks to fly through the streams. That means the twin showers last a long time, but they’re not usually all that noteworthy – at best, they produce no more than a handful of meteors per hour. Things are a little busier when the showers overlap, as they’re doing now. Unfortunately, the Moon will be full in a couple of days, so it’ll overpower almost all of the Taurids. The streams do produce a few especially bright meteors, but that’s about the best we can expect from the shower with a dual identity. The Taurid Complex may include some especially big, dangerous chunks of debris, and we’ll talk about that tomorrow. Script by Damond Benningfield

AUDIO: We have contact. We have initial contact – initial contact of the Soyuz capsule with the Expedition 1 crew to the International Space Station. A key milestone in the human exploration of space took place 25 years ago tomorrow. The first permanent crew took up residence in the International Space Station. And people have been living on the station ever since. They weren’t the first to actually visit the station. Several groups of astronauts and cosmonauts had spent time assembling the early pieces of the station. And by November 2000, it was ready for full-time occupancy. The Expedition 1 crew was commanded by American astronaut Bill Shepherd, and included Russian cosmonauts Sergei Krikalev and Yuri Gidzenko. They launched on October 31st, from Kazakhstan: AUDIO: 4, 3, 2, 1, we have ignition – we have ignition and liftoff. Liftoff of the Soyuz rocket, beginning the first expedition to the International Space Station and setting the stage for permanent human presence in space. After arrival, they had a lot of work to do to get the station ready, as Shepherd described a decade later: SHEPHERD: So the first week was really living in a sleeping bag, running around with a checklist and a bunch of tools, trying to get this stuff all to get cranking. Shepherd and crew spent more than four months getting the station cranking. Since then, almost 300 people from more than two dozen countries have lived and worked there – an unbroken presence in space. Script by Damond Benningfield

Like other buildings, observatory domes can outlive their usefulness. They may not be big enough for the latest telescopes. The light from encroaching cities can make it hard for them to see the heavens. Or time may just catch up to them. Many domes and related buildings have been torn down. Others have been converted into offices or libraries. And still others have been abandoned – left to the elements and the ravages of time. Several of these buildings are scattered around the country – in places like Illinois and the woods of Michigan, for example. Their walls are covered with graffiti, their floors with water and trash, their spaces haunted by the ghostly memories of nights under the stars. Perhaps the most famous abandoned observatory sits on a grassy knoll in Cleveland. It was built by the men who founded Warner and Swasey, a machine-making company. They were amateur astronomers who devoted part of their business to building telescopes – including the first big telescope at McDonald Observatory. In 1919, they donated an observatory to Case University. They equipped it with a telescope of their own making. Bigger telescopes followed. The beautiful building was abandoned in 1982. Its telescopes had been sent elsewhere, and its staff moved into other quarters. Today, the building is decaying and dangerous – a ghostly presence beneath the stars on Halloween night. Script by Damond Benningfield

The night sky is filled with monsters. And none are more fearsome than the Gorgons – three sisters who were so hideous that a single glance at them turned the observer to stone. One of them was beheaded by Perseus the hero. His constellation shows him holding the head, which is outlined by four stars – the Gorgons. In mythology, two of the sisters were immortal. But the third, Medusa, was not. Perseus managed to lop off her head with the help of the gods. They gave him an invisibility cloak, a diamond sword, and a bronze shield. He could safely view the Gorgons by looking at their reflection in the shield. Perseus used Medusa’s head to destroy the sea monster, Cetus, which was about to kill the princess Andromeda. Cetus and Andromeda have their own constellations, as do Andromeda’s parents. The brightest star in Medusa’s head is Algol – a name that means “head of the demon.” It’s low in the northeast in early evening and climbs high across the sky later on. The other Gorgons form an arc to the right of Algol. One is fairly easy to spot, while the other two require a darker sky. All four of the Gorgon stars are bigger, heavier, and brighter than the Sun. Algol is a couple of hundred light-years away, while the other three are about a hundred light-years farther. The Gorgons form a demonic presence in the sky – shining down on Halloween weekend. We’ll have more about Halloween tomorrow. Script by Damond Benningfield

A young “cotton-candy” planet is hastening its own demise. As it dips close to its star, it appears to trigger giant explosions that erode the planet’s atmosphere. The planet orbits HIP 67522, a star roughly 400 light-years from Earth. The star is a little bigger and heavier than the Sun, but less than one percent the Sun’s age. Such young stars generate strong magnetic fields. Lines of magnetic force tangle and snap, producing powerful flares. The planet, HIP 67522 b, orbits just a few million miles from the star, so it already receives hefty doses of radiation and charged particles. A European space telescope, Cheops, has seen 15 flares that are tied to the planet’s orbit around the star. The planet may gather magnetic energy as it whips around the star. Waves of magnetic force ripple outward like the wake of a ship. When the waves hit a stormy spot on the star, they trigger a giant flare. That douses the planet with six times more radiation than it would receive otherwise. HIP 67522 b is almost as big as Jupiter, the giant of our own solar system. But it’s only about one-quarter of Jupiter’s mass. That makes the planet especially puffy, like cotton candy. But as it’s zapped by the star, some of its atmosphere is blown away. In a hundred million years or so, it could shrink to less than half its current size – a shrinkage caused by its close orbit around the star. Script by Damond Benningfield